1. Field of the Invention
The present invention relates to an option-identifying system that identifies the locations of optional devices such as paper trays used in an electrophotographic printer, the optional devices being in a stacked configuration, inserted into the printer. The present invention also relates to a method where a host apparatus identifies the locations of one or more low optional devices electrically connected to the host apparatus and the low individual low optional devices can also identify their locations. The present invention also relates to a system in which the host apparatus individually communicates control signals with the respective low optional devices.
2. Description of the Related Art
Printers and copying machines are provided with option paper trays that hold paper of different sizes and orientation are detachable from and attachable to the main body.
{Operation for Assigning Locations to Option Trays}
FIG. 17 illustrates conventional option trays when they are inserted into a printer.
Referring to FIG. 17, a printer 100 incorporates a printer controller 101 and an option tray interface connector 102. Optional trays 200A and 200B have an upper interface connector 201A and 201B and lower interface connectors 202A and 202B, projections 203A and 203B, detection switches 204A and 204B, and tray controllers 205A and 205B.
The printer controller 101 controls the overall operation of the printer 100 including the option trays 200A and 200B. The printer controller 101 communicates various signals with the option tray 200A over a serial signal transmit/receive line 400. The serial signal transmit/receive line is connected to the option tray controller 205A of the upper option tray 200A via the option interface connector 102 of the printer 100 and the upper interface connector 201A of the upper option tray 200A.
The transmit/receive line 300 is further connected through the lower interface connector 202A of the option tray 200A with the upper option tray 200B. The stacked option trays 200A and 200B are of the same configuration. The printer 100 usually incorporates a standard tray, not shown, therein. Thus, a tray (i.e., 200A) located immediately under the standard tray is usually referred to as the 2nd tray and a tray (i.e., 200B) next to the 2nd tray is referred to as the 3rd tray.
The option trays 200A-200B have upright projections 203A-203B such that when the option trays 200A-200B are stacked, the projection 203B fits to the immediately upper option tray 200A to push a detection switch 204A provided on the immediately upper option tray 200A. The detection switches 204A-204B are connected to the option tray controllers 205A-205B.
The option tray controller recognizes that a corresponding option tray is at the location of the 2nd option tray if the detection switch is pushed. The option tray controller recognizes that a corresponding option tray is at the location of the 3rd option tray if the detection switch is not pushed.
In this manner, the option tray controller 205 of an option tray determines where the option tray is located. Then, when the printer controller 101 receives a print command from a host computer, not shown, the printer controller 101 sends a paper-feed command over the transmit/receive line 300 to the option trays 200A and 200B simultaneously under a predetermined protocol.
The paper-feed command include, for example, information on the location of a corresponding option tray that holds print medium of the size, type, and orientation specified by the print command. The option tray controller makes a check to determine whether the received location information matches the one assigned to the option tray. If they do not coincide with each other, then the option tray controller will simply ignore the location information. If they coincide with each other, then the option tray controller causes a feed motor and a paper sensor, not shown, to operate in order to feed print paper to the printer 100, thereby initiating a printing operation.
However, the conventional printer 100 of the aforementioned construction suffers from the problem that only up to two stacked option trays can be identified. When three or more of the option trays are stacked, all of the detection switches 204A-204B of the stacked option trays except for the detection switch 204B of the bottom option tray will be pushed. As a result, only the bottom option tray can be identified. One way of solving this drawback is to employ a DIP switch in each option tray and set the DIP switch in accordance with the location of the option tray. However, this requires the user to remember the setting of the DIP switch and the location to which the DIP switch is set.
This conventional configuration also suffers from the problem that if the user does not remember the setting of the DIP switch or the user makes a mistake when setting the DIP switch, the paper is not fed from the right option tray.
{Operation of the Printer Controller}
FIG. 18 is a flowchart showing the operation of the printer controller in which a check is made to determine whether option trays are present or absent.
At step S501, the printer controller 101 sends a SW-OFF inquiring command to the option trays over the serial transmit/receive line 300. The SW-OFF inquiring command is a command that inquires the option trays whether their detection switches are in the off-state.
At step S502, shortly after the transmission of the command, the printer controller 101 starts to count an elapsed time. If the printer controller 101 does not receive a reply from any one of the option trays over the transmit/receive line 300 before the printer controller 101 has counted time up to a predetermined time length, then the printer controller 101 stores data xe2x80x9c2ND=ABSENTxe2x80x9d and xe2x80x9c3RD=ABSENTxe2x80x9d at step S508.
At step S503, if the printer controller 101 receives a SW-OFF reply from one of the option trays over the transmit/receive line 300, then the printer controller 101 sends at step S504 a SW-ON inquiring command to the option tray over the transmit/receive line 300. The SW-OFF reply indicates that the detection switch is in the off-state. The SW-ON inquiring command is a command that inquires whether the detection switches of the option trays are in the on-state. If the printer controller 101 does not receive at step S505 a SW-OFF reply from the option trays over the transmit/receive line 300 before the printer controller 101 has counted up to a predetermined time length, then the printer controller 101 stores at step S509 data xe2x80x9c2ND=OFFxe2x80x9d and xe2x80x9c3RD=ABSENTxe2x80x9d at step S510.
If the printer controller 101 receives a SW-ON reply from one of the option trays over the transmit/receive line 300 at step S506, the printer controller 101 stores at step S507 xe2x80x9c2ND=ONxe2x80x9d and xe2x80x9c3RD=OFFxe2x80x9d at step S510.
{Operation for Determining Whether Option Trays are Present or Absent}
FIG. 19 illustrates the operation for determining whether option trays are present or absent.
At step 511, the option trays receive the presence/absence polling command over the transmit/receive line 300. The presence/absence polling command is a command to inquire whether a specified option tray is present.
At step S512, the respective option trays determine whether the received command is the presence/absence polling command. If the answer at step S512 is YES, then the option trays read the state of their own detection switches at step S513. If the answer at step S512 is NO, then the program proceeds to step S516 where other command is executed.
At step S514, if the state of the switch of one of the option trays matches the presence/absence polling command, then the option tray reads the state of its own detection switch.
At step S515, the option tray sends at step a PRESENCE reply to the printer controller over the transmit/receive line 515. The PRESENCE reply indicates that the inquired option is actually present. If the answer is NO at step S514, the received presence/absence polling command is simply ignored and the program ends.
{Operation of Acquiring the Status of the Option Tray}
The printer controller 101 has a table which lists switch data of the individual option trays obtained by the operation of checking whether option trays are present or absent. The printer controller 10 reads from the table the switch data for an option tray to be specified. The printer controller 101 then sends the switch data together with an option status polling command to the option tray over the transmit/receive line 300.
A check is made at each option tray to determine whether the received switch data matches the one stored in the option tray. If the answer is YES, then the option tray sends status data that describes the print medium accommodated in the option tray to the printer controller 101 over the transmit/receive line 300. The information regarding the print medium includes the size, type, orientation, and presence and absence of the print medium. If the received switch data does not match the one stored in the option tray, then the option simply ignores the switch data and option status polling command. The printer controller 101 receives the status data from the option tray and stores it therein.
{Printing Operation}
Upon receiving a print command from a host apparatus, the print controller 101 determines, based on the status data, an option tray that meets the conditions selected by the user. Then, over the serial transmit/receive line 300, the printer controller 101 reads the switch data of the option tray specified by the user therefrom, and sends the switch data to the option tray over the transmit/receive line 300. The option tray receives the switch data from the print controller 101 over the serial transmit line 40. If the switch data matches the one stored in the option tray, the option tray feeds a print medium therefrom in accordance with the paper-feed command. If the switch data does not match the one stored in the option tray, then the option tray ignores the paper-feed command. In this manner, a page of print medium is fed from the specified option tray.
The present invention was made in view of the aforementioned drawbacks.
An option-identifying system identifies the locations of a plurality of options that are electrically connected in cascade and mounted to a main body such that the options are attachable to and detachable from the main body. The main body has a signal generating section that outputs a location-assigning signal having a plurality of bits to a first one of the plurality of options. Each of the plurality of options has a data-storing section and a location-identifying section. The data-storing section stores the locations of the plurality of options and corresponding location data that describes the locations. The location-identifying section receives the location-assigning signal and compares the received location-assigning signal with the location data to identify a location of a corresponding option. The location-identifying section inverts one of the plurality of bits of the received location-assigning signal, then rotates the plurality of bits of the location-assigning signal after inversion of the most significant bit, and finally outputs the location-assigning signal after rotation to a following option.
Another option-identifying system identifies the locations of a plurality of options that are electrically connected in cascade and mounted to a main body such that the options are attachable to and detachable from the main body. The main body has a signal-generating section that outputs a location-assigning signal having a plurality of bits to a first one of the plurality of options. Each of the plurality of options has a data-storing section and a location-identifying section. The data-storing section stores the locations of the plurality of options and corresponding location data that describes the locations. The location-identifying section receives the location-assigning signal and compares the received location-assigning signal with the location data to identify a location of a corresponding option. The location-identifying section outputs the location-assigning signal having a number of bits different from the received location-assigning signal to a following option. The option identifying section may output the location-assigning signal having one more bit or less bit than in the received location-assigning signal to the following option.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.